A follow-up study was conducted until the end of 1980 on 28, 643 rural inhabitants who had undergone mass health screening between 1971 and 1978. For those who died, the causes of death were confirmed by death certificates.
The results obtained were as follows:
1) During the observation period, there were 876 death (about 3% of participants). The mortality was three times greater for males than for females and increased with age. These differences between sexes were statistically significant except the group of 29years old or under.
2) Forty-two percent of the total deaths were for cerebro-cardiovascular diseases, 32% for malignant neoplasms and 26% for others. For males, the mortality of cerebro-cardiovascular diseases was greater than those of other causes of death. On the other hand, the mortality of malignant neoplasms was higher among females.
3) The mortality rate per 1, 000 person-years of observation was 5.2 (11.8 for males and 3.2 for females). Cause- specific mortality rates were 1.7 per 1, 000 person-years for malignant neoplasms (3.1 for males and 1.2 for females); 1.2 for cerebrovascular diseases (2.8 for males and 0.7 for females), 0.9 for cardiovascular diseases (2.3 for males and 0.5 for females), 0.3 for accidents and 0.2 for pneumonia. The mortality rates of each aged-group according major causes of death were higher among males than among females except two groups of 29 years old or under and 70 years old or over of cerebral bleeding.

The purpose of this study is to establish the normal physiological values of glycosylated hemoglobin (HbA₁ and HbA_1C) among Japanese rural inhabitants and to evaluate its potential as a screening tool for diabetes mellitus. Six hundred and seventy-five people aged 35-64 years (210 males and 465 females) were examined. Oral glucose tolerance tests were perfomed on 135 inhabitants of them by giving a 50-gm.
Frequency distributions of HbA₁ and HbA_1C fitted approximately to the log-normal distribution.
Geometric means and standard deviations in bracket were 7.95 (1.11)% for HbA₁ in men, 8.13 (1.12)% for HbA₁ in women, 5.17 (1.10)% for HbA_1C in men and 5.16 (1.11)% for HbA_1C in women
Group average values of HbA₁ and HbA_1C tended to increase with age in both men and women except a male group aged 60 years and over. There were no significant differences between mean values of glycosylated hemoglobin in men and those in women. HbA₁ was positively correlated with age in women and negatively correlated with hemoglobin in both men and women. HbA_1C was positively correlated with age in men and women, body mass index, systolic blood pressure and serum cholesterol in women, and negatively correlated with hemoglobin in men.
In order to evaluate glycosylated hemoglobin as a screening tool for the identification of unknown persons with diabetes, we calculated the sensitivity (the extents to which the participants who were found to have a diabetic OGTT also had an abnormal glycosylated hemoglobin) and specificity (the extents to which the participants who were not diabetic had normal glycosylated hemoglobin). The sensitivities for the person aged 59 years or under using HbA₁ were 72.7-100% and the specificities 67.3-75.0 percent. Futhermore the sensitivities for the same aged person using HbA_1C were 81.8-100% and the specificities 78.8-81.3 percent. The validities for both HbA₁ and HbA_1C were higher than those for glucosuria or blood glucose. But glycosylated hemoglobin was not useful as a screening tool for the person aged 60 years and over because of the low specificity.

During the 1970's many cases of serious silicosis occurred among migrant workers doing tunnel construction.
We studied the prevalence of silicosis in the eastern part of Toyama prefecture. Questionnaires were sent to all male inhabitants aged 30 or over in the five selected areas. Eight hundred and eighty-five of respondents (41%) had worked as migrant workers. Of these, 580 men (66%) had worked on the job with exposure to dust such as tunnel construction. Of this number, 482 men were examined by chest roentgenography. Of the 482 migrant workers whose job exposed them to dust, 424 silicosis cases (88%) were found. These patients included 195 cases of category 1, 123 cases of category 2, 59 cases of category 3 and 47 cases of category 4 silicosis.
Most of the patients retired and returned to their home villages without having been given any diagnosis and medical care at their places of employment. The silicosis in 297 cases (70% of the total number of disease patients) was first detected in the course of our research.
Two thousand and seventy-seven of the respondents for questionnaire in 1977 and 1978 were followed-up until the end of 1983. For those who died, the causes and dates of death were confirmed by death certificates. The mean person-years of observation per a person was 5.9. The subjects were divided into three groups.
The mortality rate per 1, 000 person-years of migrant workers who had worked in jobs with exposure to dust was 22.3. The mortality rate was significantly higher than that of migrant workers who had not worked in jobs with exposure to dust (14.9) and those who were not migrant workers (9.1). Especially significance is the excess mortality rate of migrant workers whose jobs exposed them to dust in ages 40 to 69.
The mortality rates for pulmonary tuberculosis, pneumonia & bronchitis and pneumoconiosis among migrant workers whose jobs exposed them to dust were higher than those among non-migrant workers.

The purpose of this study is to investigate the prevalence of and to classify the types of silicosis patients who were working at that time as migrant workers in the eastern part of Toyama Prefecture. Migrant workers are known in Japanese as “dekasegi” This term refers to workers who migrate seasonally from their home towns to areas where work is more available.
Questionnaires were sent to all male inhabitants aged 30 or over in the selected five areas. Eighty-seven percent of the questionnaires were answered and returned. Based on the results, 482 inhabitants were selected as migrant workers with experience in jobs where they were exposed to large amount of dust. Chest roentgenography and subjective symptoms were examined in these subjects.
The results obtained were follows;
(1) Eight hundred and eighty-five of the respondents (41%) had worked as migrant workers.Of these, 580 men (66%) had worked in jobs with exposure to dust.
(2) Of the 482 migrant workers whose jobs exposed them to dust, 424 silicosis cases (88%) were found by chest roentgenographic examination. Silicosis is classified into four types according to the national Pneumoconiosis Law on the basis of chest roentgenographic findings. These patients included 195 cases of type 1, 123 cases of type 2, 59 cases of type 3 and 47 cases of type 4 silicosis.
(3) The prevalence of disease symptoms in the silicosis patients included ; cough 39%, phlegm 40%, shortness of breath 41%, palpitations 17% and wheezing in 20% of the cases. The silicosis patients showed a higher frequency of respiratory disease symptoms than those dust-exposed workers who did not evidence signs of silicosis.
(4) The silicosis patients were found in 98% of the migrant workers whose exposure to dust lasted a period of more than 20 years, 89% in men whose work was between 10 and 19 years and 76 % in men who had worked less than 10 years.
(5) The silicosis in 297 cases (70% of the total number of disease patients) was first detected during the examinations in the course of this research.